On Oct. 12, a small asteroid almost the size of an office building will make a close approach to Earth, passing at a distance roughly 27,000 miles away from the planet.
According to NASA, the asteroid, 2012 TC4, poses no danger but will better the agency's capabilities for detecting and tracking near-Earth objects, or NEOs, that could pose a hazard in the future.
"The campaign to reacquire, track and characterize TC4 is exercising both NASA’s efforts and those of our international partners," Laurie Cantillo said.
Cantillo is the Lead Communications Specialist with NASA's Planetary Science Division.
The goal of this partnership is to detect, track and characterize objects approaching Earth and exchange the data collected so that the best information is made available worldwide for any potential impact hazard, Cantillo added.
"NASA participates with astronomers from other nations in the International Asteroid Warning Network for this effort," she said.
Based on NASA's preliminary observations, TC4 is expected to be 30 meters or less in size.
"As the asteroid approaches the Earth, additional observations will allow us to define its size and shape much more accurately," Cantillo said.
The latest prediction for the close-approach distance is a little over 27,000 miles, or 50,000 km.
"That is about 13 percent of the average distance to the moon," she said. "Or to put another way, on average, the moon is about 7.7 times farther away."
"The thickness of the Earth’s atmosphere is about 300 miles, or 480 km, although it gets much, much thinner the higher you go," she said.
In order for the object to enter Earth's atmosphere, the asteroid would have to be at least that close.
Astronomers using the European Southern Observatory reacquired the object in late July and, since then, have made several observations of TC4.
NASA is tasked with the detection and tracking of any Earth-approaching asteroid or comet that could be a significant impact hazard to the Earth. In order to do this, astronomers catalog all NEOs that are at least 140 meters in size, Cantillo said.
"NASA is already doing this for all potentially hazardous asteroids we are able to detect and track," she said. "However, estimates for the overall population of near-Earth asteroids are significantly greater than what we have observed to date. That is why NASA continues to conduct a telescopic survey program."
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By using large optical telescopes, astronomers are able to observe objects like TC4 and use their observations to calculate their orbits.
Astronomers from around the world send their observations to the International Astronomical Union and the NASA-supported Minor Planet Center, which maintains a database of all known asteroids and comets in the solar system.
Other astronomers, both professional and amateur, then use that position information to perform follow-up observations, and from that an orbit is calculated and refined with additional observations.
"Each new observation helped refine the orbit calculations, so that now the position of the object at any time is known very precisely," Cantillo said.